Biochemical characterization of a flavodiiron protein from bird parasite Histomonas meleagridis: superoxide as a reaction intermediate.

Histomonas meleagridis is a parasitic protozoan which causes histomoniasis (blackhead disease) in a wide range of birds, including domesticated chickens and turkeys, representing a significant health problem in avian veterinary medicine. Despite being classified as an anaerobic parasite, H. meleagridis can survive transient exposure to oxygen while little is known about the mechanisms that allow this organism to cope with exposure to varying oxygen levels.

Dominant-negative NARS1 R534* mutation causes wild-type subunit poisoning and heterodimer predominance in cells.

Aminoacyl-tRNA synthetases (aaRSs) catalyze the aminoacylation of tRNA with their cognate amino acids, an essential step in protein biosynthesis. While biallelic mutations in aaRSs often result in severe multi-organ dysfunction accompanied by developmental delays, monoallelic mutations typically cause milder, tissue-specific symptoms. However, a de novo monoallelic nonsense mutation (R534*) in the asparaginyl-tRNA synthetase (AsnRS)-resulting in a premature stop codon and 15-residue C-terminal truncation-has been identified in multiple families and is associated with severe neurodevelopmental symptoms.

MicroRNA (miRNA) in Plasma Small Extracellular Vesicles (sEV) as Potential Early Indicators of Dairy Cow Subfertility.

Pregnancy and live birth rates are commonly used metrics to define fertility in humans and animals. The impact of aberrant microRNA (miRNA) expression on fertility-related genes represents a significant knowledge gap in understanding post-transcriptional regulatory mechanisms associated with reproductive dysfunction. Identifying subfertility markers is therefore critical to the success of fertility intervention strategies, particularly in agriculture, where sustainable farming practices are linked to overall economic performance.

CryoEM Structures of Antibodies Elicited by Germline-Targeting HIV MPER Epitope-Scaffolds.

Applying cryoEM to small protein complexes is usually challenging due to their lack of features for particle alignment. Here, we characterized antibody responses to 21 kDa HIV membrane-proximal external region germline-targeting (MPER-GT) immunogens through cryoEM by complexing them with 10E8 or Fabs derived from MPER-GT immunized animals. Distinct antibody-antigen interactions were analyzed using atomic models generated from cryoEM maps.

Targeting Sialidase to PD1 Enhances T cell Function and Tumor Control.

Immune therapies targeting the PD1 axis have transformed outcomes in cancer treatment by enhancing T cell-mediated immune responses. However, many tumors evade immune clearance through orthogonal escape mechanisms. Excessive production of immunosuppressive sialic acid-containing glycans (sialoglycans) can impair immune surveillance by recruiting inhibitory Siglecs to the immune synapse where, like PD1, they act as checkpoints for cell activation.

Enantioselective Pd-Catalysed Nucleophilic C(sp)-H (Radio)fluorination.

Despite increasing demand for chiral fluorinated organic molecules, enantioselective C-H fluorination remains among the most challenging and sought-after transformations in organic synthesis. Furthermore, utilizing nucleophilic sources of fluorine is especially desirable for F-radiolabelling. To date, methods for enantioselective nucleophilic fluorination of inert C(sp)-H bonds remain unknown.

A vascular-associated fibroblastic cell controls pancreatic islet immunity.

The immune protection of pancreatic β cells has three layers: anatomical, with their distribution in 1 million islets; central, with the thymic deletion of β cell-specific T cells; and peripheral, with inhibitory cellular networks. The failure of the latter leads to most spontaneous type 1 diabetes and all diabetes induced by checkpoint inhibitor therapy. Because CD4 T cells initiate disease, major histocompatibility complex (MHC) class II-expressing cells are central to the onset.

Synthetic approaches to enhance biological carbon capture.

Biologically driven strategies to remove carbon dioxide from the atmosphere are gaining traction as long-term means for atmospheric correction. Many ongoing research efforts focus on enhancing the Calvin-Benson-Bassham (CBB) cycle with notable focus on the rate-limiting enzyme ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCO), aiming to alter its catalytic efficiency, substrate specificity, or cognate regulatory pathways. Beyond these strategies, novel approaches to provide energy to the CBB cycle or synthetic pathways for in vivo autotrophy have opened the door to engineerable carbon-negative biosynthesis.

Streamlined Fragment-Based Discovery Platform for Targeting Structured RNAs.

Fragment-based drug discovery typically relies on specialized spectrometric methods to identify low-affinity compounds that bind to biomolecules. Here, we report a proof-of-concept study on the development of a streamlined fragment-based screening platform for small molecules targeting RNA. This method employs low molecular weight fragments appended with a diazirine reactive moiety and an alkyne tag.

From Mono--Protected Amino Acids to Pyridones: A Decade of Evolution of Bifunctional Ligands for Pd(II)-Catalyzed C-H Activation.

ConspectusFunctionalization of carbon-hydrogen (C-H) bonds has emerged as a powerful strategy in modern organic synthesis, offering efficient routes to build molecular complexity from simple and abundant substrates. Among various transition-metal catalysts, palladium(II) complexes have proven particularly versatile for C-H activation, owing to the diverse reactivity of carbon-palladium bonds. To advance this approach, the discovery of ligands that can accelerate C-H activation as well as subsequent steps in the catalytic cycle is the pivotal driving force.

Chemoselective Benzylic C-H Deuteration Using Deuterium Gas.

Chemoselective incorporation of hydrogen isotopes is a useful tool for drug discovery and mechanistic investigation. While late-stage C-H functionalization via hydrogen isotope exchange (HIE) offers a straightforward route to isotopically labeled compounds, existing methods often use deuterated solvents which are not feasible for tritium labeling. Hence, direct use of simple deuterium gas for isotopic labeling is highly desirable.

The dual non-competitive CXCR1/2 inhibitor ladarixin impairs neutrophil extravasation without altering intravascular adhesion.

In many acute and chronic inflammatory disorders, recruitment of neutrophils plays a critical role in preventing disease severity and ensuring survival. On the other hand, neutrophil accumulation during inflammation can also favor disease progression in diseases such as autoimmune disorders, cancer or during ischemia-reperfusion injury. Therefore, blocking neutrophil influx has been considered an interesting therapeutic concept in diseases with overwhelming neutrophil responses.

Intravitreal NHS-Biotin Injection and Immunohistochemistry to Label and Image Protein Transport in the Mouse Optic Nerve.

The process of moving proteins and organelles along the axon is essential for neuronal survival and function, ensuring proper communication between the cell body and distant synapses. The efficient and precise delivery of proteins via axon transport is critical for processes ranging from synaptic plasticity and neurotransmission to neuronal growth and maintenance. However, the identities of all the transported proteins have only recently begun to be investigated.

Crystal structures of agonist-bound human cannabinoid receptor CB.

Cannabinoid receptor 1 (CB) is the primary target of the partial agonist Δ-tetrahydrocannabinol (Δ-THC), the psychoactive constituent of marijuana. Here we report two agonist-bound crystal structures of human CB in complex with a tetrahydrocannabinol (AM11542) and a hexahydrocannabinol (AM841). The two CB-agonist complexes reveal important conformational changes in the overall structure relative to the antagonist-bound state, including a 53% reduction in the volume of the ligand-binding pocket and an increase in the surface area of the G protein-binding region.

Human monoclonal antibodies targeting A35 protect from death caused by mpox.

The 2022 mpox outbreak highlighted the serious threat of monkeypox virus (MPXV), yet effective treatments are lacking. From an mpox-convalescent individual, we identified three high-affinity human monoclonal antibodies (mAbs) (named EV35-2, EV35-6, and EV35-7) that target the A35 protein in MPXV. These antibodies block viral spread in vitro and protect mice against lethal MPXV and vaccinia virus infection via both Fc-dependent and independent mechanisms.

Comparative analysis of the extent of protein-protein interactions in icosahedral viral capsids.

Nonenveloped viruses package, carry, and deliver their genomes to the targeted cells using protein shells known as capsids. The viral capsids come in different shapes and sizes, most exhibiting helical or icosahedral symmetries. Here, we analyzed 634 icosahedral capsids at high resolution (<4 Å) from 39 virus families with T-numbers ranging from 1 to 9 and evaluated the aggregated buried surface areas (BSAs) at the unique interfaces as a measure of capsid strength and protein-protein interactions (PPIs).

A modification to heptad repeat 1 of gp41 improves yield and/or quality of soluble pre-fusion HIV-1 envelope glycoprotein trimers.

Unlabelled: Native-like HIV-1 envelope glycoprotein (Env) trimers, exemplified by the SOSIP design, are widely used as immunogens, analytical antigens, and for structural studies. These vaccine research and development programs require trimers that are based on multiple HIV-1 genotypes. While a wide range of protein engineering strategies can produce SOSIP trimers from most Env gene sequences, there are still examples of trimers that are expressed only at impractically low yields or that are unstable.

Directed evolution-based discovery of ligands for in vivo restimulation of chimeric antigen receptor T cells.

Chimeric antigen receptor (CAR) T cell therapy targeting CD19 elicits remarkable clinical efficacy in B cell malignancies, but many patients relapse owing to failed expansion and/or progressive loss of CAR-T cells. We recently reported a strategy to potently restimulate CAR-T cells in vivo, enhancing their functionality by administration of a vaccine-like stimulus comprised of surrogate peptide ligands for a CAR linked to a lymph node-targeting amphiphilic PEG-lipid (amph-vax). Here we demonstrate a general strategy to discover and optimize peptide mimotopes enabling amph-vax generation for any CAR.

Solid-phase synthesis of a pyrrole library and identification of bioactive compounds.

Pyrrole derivatives represent a privileged scaffold in medicinal chemistry due to their frequent presence in biologically active compounds. Herein, we report the solid-phase synthesis of a combinatorial library consisting of 211 pyrrole derivatives using a split-and-pool strategy based on the Hantzsch pyrrole synthesis. The pooled compounds were evaluated in a cell proliferation assay using the human lymphoblastoid cell line P493-6, a model with Myc-regulated growth.

Characterization of the glycoproteins of fish and amphibian influenza B-like viruses.

Influenza-like virus sequences previously identified in fish and amphibians cluster as a sister clade of influenza B viruses but remain largely uncharacterized. We demonstrate that salamander influenza-like virus (SILV) hemagglutinin (HA) is functionally divergent from influenza B virus HA and does not bind to α2,3- and α2,6-linked sialic acids. However, the HAs of Siamese algae-eater influenza-like virus (SAEILV) and chum salmon influenza-like virus (CSILV) bind to α2,3-linked sialic acid.

The p400 complex promotes HIV-1 latency by suppressing viral transcription and altering the host cell state.

Eradicating HIV-1 is complicated by latently infected CD4+T cells harboring dormant proviruses capable of reactivation. Through a pooled shRNAmir screen targeting human chromatin regulators, we identified EP400, a member of the p400 chromatin remodeling complex, as a potent inhibitor of HIV-1 transcription in Jurkat and primary CD4+T cells. EP400 and its complex partner DMAP1 co-localize with paused RNA Polymerase II (RNAPII) at transcriptional start sites of protein-coding genes and their depletion modestly reduced RNAPII pausing.

Modeling environmental inhalant exposure in rheumatoid arthritis.

The mucosal origins hypothesis posits that environmental inhalant exposures, including cigarette smoke (CS) and crystalline silica (c-silica), trigger immune responses in the lung mucosa, an extra-articular site, which precede initiating events of rheumatoid arthritis (RA) pathogenesis in distant joints. Epidemiological data strongly associates these exposures with RA risk, especially in genetically susceptible individuals carrying HLA-DRB1 alleles, and with the production of autoantibodies such as anti-citrullinated peptide antibodies (ACPA) and rheumatoid factor (RF). However, establishing causality remains challenging due to unsynchronized exposure and disease onset and the lack of suitable animal models to study early disease events.

Exogenous estrogen enhances T cell activation in male primates.

Estrogen influences T cell development and enhances infection resistance in females, but its immunological effects during gender-affirming hormone therapy (GAHT) remain poorly understood. Here, we characterize immune adaptations in male rhesus macaques (RMs) treated with 17β-estradiol (E2) or placebo over 7 months. E2 therapy suppressed endogenous testosterone production, induced female physical traits, and altered blood cell counts and chemistry profiles.

Plasma apolipoproteins and memory function in alcohol use disorder: Findings in male C57BL/6J mice and men suggest a role for APOAI.

Background: Memory impairment is frequent among alcohol use disorder (AUD) patients, and we lack specific biomarkers to detect it. Certain apolipoproteins were linked to cognition, and carrying the APOE4 gene is a vulnerability factor to memory impairment in AUD patients. We explored memory deficits in alcohol-dependent male mice and humans versus controls, and their relationship to Apolipoprotein AI (APOAI), apolipoprotein B (APOB), and apolipoprotein E (APOE) plasma levels.